Polygenic risk score
Tourette Syndrome
ICD-11 8A05 · Movement disorders
The Tourette Syndrome polygenic risk score summarizes common-variant liability from the 2019 Yu PGC GWAS. Tourette is the smallest psychiatric cohort in the PGC set, which limits PRS power — but the genetic overlap with OCD and ADHD is well-established.
Tourette Syndrome shares notable common-variant architecture with OCD (rg ≈ 0.41) and ADHD — reflecting a compulsive/tic-spectrum that crosses traditional diagnostic categories.
At a glance
Tourette syndrome is a moderately heritable tic disorder with a small but growing GWAS. Your score reflects the 2019 PGC Tourette GWAS.
Tourette syndrome is a neurodevelopmental tic disorder typically beginning in childhood, characterized by motor and vocal tics. Twin heritability is around 50-77%. Tourette shares substantial common-variant risk with OCD and ADHD.
What the GWAS actually found
The Yu et al. 2019 Tourette GWAS (American Journal of Psychiatry) combined 4,819 cases and 9,488 controls, identifying 1 genome-wide significant locus. A top-hit gene named in the paper is FLT3, though the locus count reflects the comparatively small cohort size rather than a weak genetic signal.
Twin-study heritability for Tourette is among the highest in psychiatry (~0.70–0.80). The gap between twin heritability and current SNP-based heritability is substantial — reflecting cohort size rather than a genuinely low common-variant contribution.
How to read your percentile
Below 25th
Lower common-variant liability than most of the reference cohort. Tourette is rare (~0.3–1% prevalence) regardless of PRS percentile.
25th–75th
Typical range — near the population average. PRS noise is high at this cohort size.
Above 75th
Elevated common-variant liability. Interpret with caution — the Tourette PRS is less well-powered than other psychiatric scores, so individual percentiles carry more uncertainty.
What this does not tell you
The Tourette PRS is underpowered relative to other psychiatric PRS because of the smaller cohort size. Variance explained is modest and cross-ancestry transportability is especially reduced given the smaller training base. Interpret percentiles accordingly — the signal is noisier than for conditions with larger GWAS.
The score cannot predict tic severity, tic type (motor vs vocal), age of onset, or comorbid OCD/ADHD presentation. Comprehensive Behavioral Intervention for Tics (CBIT) is the first-line evidence-based treatment — response is not genetically predicted by this score.
Related traits
Tourette Syndrome shares common-variant architecture with several other psychiatric conditions. Genetic correlations (rg) reflect how often the same variants move risk for both traits in the same direction.
Frequently asked questions
Why does Tourette have only one genome-wide locus?
Cohort size, not biology. The 2019 Yu meta-analysis combined ~14,000 participants — small by psychiatric-GWAS standards. As the PGC Tourette cohort grows, additional loci will reach genome-wide significance. Twin-study heritability suggests substantial undiscovered common-variant signal.
Does the score predict tic severity?
No. The GWAS case definition is presence/absence of Tourette, not symptom severity. Tic-severity-specific PRS is an open research question.
How much does Tourette overlap genetically with OCD?
Substantially — the common-variant correlation is approximately 0.41 (Davis 2013). Approximately 30–50% of Tourette patients meet criteria for comorbid OCD at some point, consistent with shared genetic architecture.
Should this score influence tic treatment?
No. This is a research and educational tool. Tic management — CBIT, pharmacotherapy in severe cases — is clinical and evidence-based, not genetically prescribed.
Sources
- Yu et al. 2019, American Journal of Psychiatry. doi.org/10.1176/appi.ajp.2018.18070857
- PGC Tourette Syndrome Working Group. pgc.unc.edu/for-researchers/working-groups/tourette-syndrome-workgroup/
- Davis et al. 2013 — OCD & Tourette genetic overlap. doi.org/10.1371/journal.pgen.1003864
Want your own polygenic risk score?
Upload your AncestryDNA or 23andMe raw data to get the ADHD and Anxiety preview free, or unlock all 13 traits for $29 (launch pricing).
Upload your file